This invention relates generally to rotary machines and more particularly, to methods and apparatus for assembling combustion turbine engines.
Many known combustion turbine engines ignite a fuel-air mixture in a combustor and generate a combustion gas stream that is channeled to a turbine via a hot gas path. Compressed air is channeled to the combustor by a compressor. Combustor assemblies typically have fuel nozzles that facilitate fuel and air delivery to a combustion region of the combustor. The turbine converts the thermal energy of the combustion gas stream to mechanical energy that rotates a turbine shaft. The output of the turbine may be used to power a machine, for example, an electric generator or a pump.
Many known fuel nozzle assemblies have a variety of components manufactured from a variety of materials that are joined together with brazed joints. These materials, including the brazed joints, may have differing thermal growth properties which have differing rates and magnitudes of thermal expansion and contraction.
Fuel nozzle assemblies are normally within near proximity of the combustion region of the combustor assemblies. Due to the near proximity to the combustion regions, the nozzles and their constituent components may experience temperature variations ranging from substantially room temperature of approximately 24° Celsius (C.) (75° Fahrenheit (F.)) to operating temperatures of approximately 1316° C. to 1593° C. (2400° F. to 2900° F.). Therefore, the large range of temperature variations in conjunction with the differing thermal expansion and contraction properties of the fuel nozzle assemblies materials causes stresses in the brazed joints, including the brazed joints associated with combustor end covers and fuel nozzle inserts.